In the no-holds-barred battle for the Bihar voter's mandate, as things stand, the politically expedient coalition of Nitish Kumar and Lalu Prasad has a slim advantage over Narendra Modi's firepower, a HuffPost-CVoter pre-poll survey has found.

The BJP-led alliance got a 40% vote share in the poll, one percentage point more than what they managed during the 2014 general elections, while the RJD-JDU-Cong alliance got a 43% vote share. This, in the bipolar contest, translated into 124 seats for the RJD alliance, with the BJP alliance managing only 102. Bihar has 243 assembly seats.

The Bihar elections will be a make or break fight for both sides. For Narendra Modi and the BJP, a loss in Bihar will signal an erosion of the formidable political capital it had managed to accumulate during the 2014 general elections. After the rout in Delhi elections, a loss in Bihar will be a disaster for Modi's personal standing and will take the sheen off his confidante and BJP president Amit Shah. For Nitish Kumar, who broke off his long alliance with BJP and has partnered with his life-long nemesis Lalu Prasad, just to keep the Modi Juggernaut at bay, a loss would be his career's greatest setback. It would all but finish Lalu Prasad's prospects as well.

The HuffPost-CVoter pre-poll survey conducted 10,636 interviews covering all 243 segments in Bihar in August last week and September 1st week.

"This election is a contest between arithmetic and chemistry. This round of the survey is all about the arithmetic. And undeniably, the Nitish-Lalu alliance have a 3 percentage points seat share lead there," said CVoter founder and editor Yashwant Deshmukh. "But their coalition will face significant challenges in the next two rounds which are about the chemistry--the seat sharing stage and the candidate selection stage," he added.

Nitish's JD(U) and Lalu Prasad's RJD have decided they will contest 100 seats each, with 40 allocated for junior partner Congress. When it comes to deciding which seats will each party contest, the internal cohesion will be put to test. It will once again be strained, with caste calculations coming into play, when the candidate selection stage comes. If they can manage these two rounds well, they would be able to sustain the lead into later stages, Deshmukh reckons.

Nitish Kumar's party, for instance, is contesting fewer seats than it won in 2010. Lalu Prasad's RJD has traditionally contested all seats in Bihar. This will make seat selection and candidate selection excessively challenging for the thin and straining bond that binds the parties together.

These stages will be relatively easy for the BJP as the NDA has been more or less settled since 2014 elections.

Another factor that favours the the NDA is the natural cohesion of the caste-based allies. "The Kushwahas, Musahirs and Paswans are in sync with BJP's traditional caste support base. There is no conflict there. Whereas the Yadav base of the RJD and the Kurmi-Koeri base of the JDU are in social and political conflict. So if the BJP fields a Yadav candidate against a Kurmi candidate of the JDU or of they field a Kurmi candidate against a Yadav candidate of the RJD, then it remains to be seen who the caste vote there will go for," Deshmukh said.

But if the JDU-RJD coalition can manage these challenges, there is no doubt they can do well in the polls, he added. An example of what their cooperation can yield, was already demonstrated in the by-polls in 10 seats of Bihar three months after the 2014 general elections. "BJP had dominated those assembly segments in the general elections. But Lalu and Nitish did a seat adjustment and did not put up candidates against each other. The BJP lost 9 out of ten seats in those polls," Deshmukh said.

So at the starting block, the RJD-JDU combine is walking in with a slim advantage. But the challenges ahead are more severe for them compared with a BJP that will come together with all its might. But if they get it right, they could walk away with this election. The lack of a prominent local leader might hurt the BJP. But ultimately, in the weeks ahead, this election will strain the every ounce of political acumen of Bihar's tallest leaders.